Prepare Docker Compose VPS deployment

[Spbd1]

Motivation

• Fix Node.js version mismatch between package.json (Node 22) and the Docker image and make the container build reproducible and production-safe.
• Ensure the Compose service exposes all documented deployment environment variables (Google Sheets, submission flags, admin/export secrets, rate/body limits, consent/schema) so the VPS environment can be configured from .env.
• Keep Postgres private inside the Docker network and bind the app to localhost so a reverse proxy (Caddy/Nginx) can handle public HTTPS.

Description

• Update Dockerfile to use node:22-alpine, install dependencies reproducibly with npm ci when package-lock.json exists, run npm run db:generate before npm run build, add a build-time arg/ENV for NEXT_PUBLIC_ENABLE_SERVER_SUBMISSION, and set runtime production envs (NODE_ENV=production, NEXT_TELEMETRY_DISABLED=1, HOSTNAME=0.0.0.0, PORT=3000).
• Update docker-compose.yml to pass the documented env vars (GOOGLE_SHEETS_WEBHOOK_URL, GOOGLE_SHEETS_WEBHOOK_SECRET, APP_BASE_URL, ENABLE_SERVER_SUBMISSION, NEXT_PUBLIC_ENABLE_SERVER_SUBMISSION, ADMIN_EXPORT_TOKEN, SUBMISSION_RATE_LIMIT_WINDOW_MS, SUBMISSION_RATE_LIMIT_MAX, MAX_SUBMISSION_BODY_BYTES, CONSENT_VERSION, SCHEMA_VERSION), add a build-time arg for NEXT_PUBLIC_ENABLE_SERVER_SUBMISSION, remove the obsolete ADMIN_DASHBOARD_PASSWORD entry, and bind the app to 127.0.0.1:3000 while keeping Postgres private (no host ports) with clarifying comments for VPS usage.
• Update .dockerignore to exclude build/context noise and local Docker artifacts (.docker/, docker-data/, docker-compose.override.yml, *.tar) in addition to existing ignores like node_modules, .next, .env, exports, .git, and logs.
• Files changed: Dockerfile, docker-compose.yml, .dockerignore.

Testing

• Ran npm run typecheck and it completed successfully.
• Ran npm run lint and it completed successfully with an existing React hook dependency warning reported (did not block the run).
• Ran npm run build and the Next.js production build completed successfully (static pages generated; build-time flag note applies).
• Attempted docker compose build and docker compose config but they could not be executed in this environment because the Docker CLI is not available (commands failed with docker: command not found).

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Codex Task